Carb Loading

Last updated: July 16, 2026

What is carb loading in an MMA weight cut?

Carb loading is the reload half of a two-part fight-week process. In the days before weigh-in, fighters cut carbohydrates low to shed water weight. Once they hit the scale, they reverse course and eat carbohydrates in large amounts to put that fuel and weight back on before they compete.

The reason it works comes down to how the body stores carbohydrate. Carbohydrate is held in muscles and the liver as glycogen, and a well-fueled fighter carries somewhere around 400 to 500 grams of it, according to Fight Fuel Nutritionist. Each gram of glycogen is stored alongside roughly 3 grams of water. Strip the glycogen out, and the water leaves with it, which is why cutting carbs drops weight fast. Pack the glycogen back in, and the water returns, which is why carb loading brings weight back up.

For a fighter, that rebound is the point. Glycogen is the main fuel for the hard, repeated bursts of a fight, so loading refills the tank. It also restores the size and body mass lost on the scale, so a fighter steps into the cage heavier and stronger than the number they weighed in at.

How carb loading works in a weight cut

The process has two stages, and they run in opposite directions.

The first stage is depletion during fight week. Fighters lower carbohydrate intake so stored glycogen and its bound water gradually drain away. Gatorade’s Sports Science Institute notes that dropping carbs below 50 grams a day for three to seven days can shed about 2% of body weight. The International Society of Sports Nutrition (ISSN) pegs the same fight-week effect at 1% to 2% of body mass. Few people picture this phase when they hear the words carb loading. Yet it sets up everything that follows.

The second stage begins the moment weigh-in ends. Rehydration comes first: the ISSN recommends oral rehydration solutions at 1 to 1.5 liters per hour with added sodium before anything else. Fast-acting carbohydrates follow at a tolerable rate of up to 60 grams per hour. From there, the total reload is large. The ISSN suggests 8 to 12 grams of carbohydrate per kilogram of body weight for fighters who ran a heavy depletion, and 4 to 7 grams per kilogram for those who restricted carbs more modestly.

How much weight comes back depends on how much time there is. A fighter with a day-before weigh-in has 24 to 30 hours to reload and rebound, while a fighter weighing in on fight day has only a couple of hours and cannot fully refill. The ISSN’s target for the whole rehydration and refueling effort is to regain at least 10% of body mass before competing.

Carb loading vs carb depletion

Most confusion around the term comes from the fact that fighters both cut carbs and load carbs within the same week. They are two sides of one strategy, separated by the weigh-in.

Aspect	Carb depletion (fight week)	Carb loading (post weigh-in)
When	The days before weigh-in	Right after weigh-in, up to the fight
Goal	Drop water weight to make the class	Refuel and rebound weight to fight strong
Carb intake	Restricted (often under 50 g/day)	High (roughly 4 to 12 g/kg)
Effect on weight	Falls as glycogen and water drain	Rises as glycogen and water return
Effect on glycogen	Emptied	Refilled

Depletion strips the tank to hit a number. Loading fills it back up to perform. A fighter who nails the first half but fumbles the second can make weight and still gas out by the second round.

Common misconceptions about carb loading

The biggest mix-up is treating this like the carb loading a marathon runner does. An endurance athlete loads to push glycogen above normal for a long race, with no weight limit in play. A fighter loads to recover glycogen and body mass after deliberately cutting both, so the goal is rebound, not supercompensation.

Another myth is that more carbs are always better. Past a point, the gut cannot keep up. Boxing News notes that high carbohydrate concentrations slow gastric emptying, which delays rehydration, and heavy intake risks bloating and stomach trouble right when a fighter needs to feel light. That is why the ISSN caps the early reload at around 60 grams per hour rather than dumping it all at once.

The third is assuming a same-day cut can be fully undone. It usually cannot. A study of elite wrestlers who lost 6% of body mass and then ate 7.1 grams of carbohydrate per kilogram found their body mass had still not returned to baseline 13 hours later. The shorter the window between weigh-in and fight, the less a fighter gets back.

Frequently Asked Questions

How much carbohydrate do fighters eat after weigh-in?

The ISSN suggests 8 to 12 grams per kilogram of body weight for fighters who did heavy glycogen depletion, and 4 to 7 grams per kilogram for a lighter cut. For an 80 kg fighter on the heavy end, that works out to roughly 640 to 960 grams of carbohydrate.

How long does carb loading take?

It depends on the weigh-in format. A day-before weigh-in gives 24 to 30 hours to reload, while a same-day weigh-in leaves only a couple of hours, which is not enough to fully refill glycogen.

Does carb loading make a fighter heavier?

Yes, and that is the intent. Because each gram of glycogen holds about 3 grams of water, reloading carbohydrate brings back both the fuel and the water weight lost during the cut.

Is carb loading the same as rehydration?

No, though they happen together. Rehydration replaces fluid and electrolytes, while carb loading replaces glycogen. The ISSN advises starting with fluids and sodium, then layering carbohydrate on top.

---

Sources

1. International Society of Sports Nutrition. “Position stand: nutrition and weight cut strategies for mixed martial arts and other combat sports.” 2025. Accessed July 2026.
   https://www.tandfonline.com/doi/full/10.1080/15502783.2025.2467909
2. Gatorade Sports Science Institute. “How to safely cut weight in combat sports.” Accessed July 2026.
   https://www.gatorade.com/resources/how-to-safely-cut-weight-combat-sports
3. Boxing News. “How to refuel after weighing in.” Updated 2025. Accessed July 2026.
   https://boxingnewsonline.net/features/how-to-refuel-after-weighing-in/
4. Fight Fuel Nutritionist. “Carbohydrate loading for athletes.” 2025. Accessed July 2026.
   https://www.fightfuelnutritionist.com/carbohydrate-loading-athletes-fueling-top-performance/
5. Barley, O. R., et al. “Self-reported methods of weight cutting in professional mixed-martial artists.” Journal of the International Society of Sports Nutrition, PMC6849211. Accessed July 2026.
   https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6849211/
6. “Effects of an overnight high-carbohydrate meal on muscle glycogen after rapid weight loss in male collegiate wrestlers.” PMC8379859. Accessed July 2026.
   https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8379859/

Related MMA Terms